The term “stem cells” designates cells which (a) have the capability of self-renewal and (b) the capability to form at least one and often a number of specialized cell types due to their asymmetrical division capability (cf. Donovan, P. J., Gearhart, J., Nature 414: 92–97 (2001)). The term “pluripotent” designates stem cells, which can essentially be differentiated into all possible cell types of the human and animal body. Such stem cells have hitherto only been obtainable from embryonic tissue or embryonic carcinoma (testicular tumor) (cf. Donovan, P. J., Gearhart, J., loc cit). The use of embryonic stem cells has been the subject of extensive public discussion, especially in Germany, and is regarded as extremely problematical. Besides the ethical and legal problems connected with embryonic stem cells, the therapeutic use of such cells also comes up against difficulties. By nature, embryonic stem cells are obtained from donor organisms, which are heterologous vis-à-vis the potential recipients of differentiated cells or tissue (hereafter referred to as somatic target cells or target tissue) developed from these cells. It is therefore to be expected, that such target cells will trigger an immediate immunological response in the potential recipients in the form of rejection.
Stem cells can be also isolated from different tissues of adult, i.e., from differentiated individuals. Such stem cells are referred to in the state of the art as “multipotent adult stem cells”. In the body they play a role in tissue regeneration and homeostasis. The essential difference between embryonic pluripotent stem cells and adult multipotent stem cells lies in the number of differentiated tissues, which can be obtained from the respective cells. Presumably, this is due to the fact that pluripotent stem cells come from sperm cells, or from cells which can produce sperm, while adult multipotent stem cells come from the body or soma of adult individuals (cf. Donovan, P. J., Gearhart, J. loc cit, Page 94), which are not capable of sperm production.
The actual problems relating to the obtaining and use of adult stem cells however lie in the rarity of these cells. Thus, in the bone marrow, stem cells are present only in the ratio of 1:10,000, in the peripheral blood of 1:250,000 and in the liver in the ratio of 1:100,000. Obtaining such stem cells is therefore very expensive and stressful for the patient. In addition the generation of large cell quantities, as required for clinical therapy, has scarcely been possible hitherto at reasonable expense.
This is contrasted by a constantly increasing need for possibilities for treatment of destroyed tissue in the form of “tissue engineering” or as cell therapy, within the framework of which skin-, muscle-, heart muscle-, liver-, islet-, nerve-, neurone-, bone-, cartilage-, endothelium- and fat cells etc. are to be replaced.
In this connection, the foreseeable development of the age and disease profile of the population in the western world is decisive, leading to the expectation of a drastic turning point in the next 10 years in the health and care sector of the western European population, including the USA and Canada. In the Federal Republic of Germany alone, the demographic development suggests a 21%-growth in population in the 45–64 year-old age group by 2015, and a 26%-growth in the over 65 age group. This is bound to result in a change in patient structure and in the spectrum of diseases requiring treatment. Predictably, diseases of the cardio-circulatory system (high pressure, myocardial infarction), vascular diseases due to arteriosclerosis and metabolic diseases, metabolic diseases such an diabetes mellitus, diseases at liver metabolism, kidney diseases as well as diseases of the skeletal system caused by age-related degeneration, and degenerative diseases of the cerebrum caused by neuronal and glial cell losses will increase and require innovative treatment concepts.
These facts explain the immense national and international research and development efforts by the specialists involved, to obtain stem cells which can be programmed into differentiated cells typical of tissue (liver, bone, cartilage, muscle, skin etc.).
The problem underlying the invention therefore resides in making available adult stem cells, the generation of which gives rise to no ethical and/or legal problems, which are rapidly available for the planned therapeutic use in the quantities required for this, and at justifiable production costs, and which, when used as “cellular therapeutics” give rise to no side effects—or none worth mentioning—in terms of cellular rejection and induction of tumors, particularly malignant tumors, in the patient in question.